We are engaged in studies examining the role of altered fucolipid synthesis in virus-transformed cells. Our studies have revealed a blockage in the synthesis of the most complex fucolipid with a concomitant increase in a simpler one(s) in oncornavirus-transformed cells. Subsequent studies have revealed a comparable blockage in fucolipid metabolism of cultured human tumor cells. Our current efforts are directed towards understanding the role of altered fucolipid metabolism in oncogenesis.